The invention relates to a bending machine for flat material, comprising a machine frame, a lower beam arranged on the machine frame and having a lower clamping tool and an upper beam arranged on the machine frame and having an upper clamping tool, with which the flat material can be fixed in a clamping plane, a bending tool moving device which is associated with one of the beams and with which a bending tool carrier with a bending tool for bending the flat material about a bending edge relative to the clamping plane can be moved into a plurality of bending positions.
A machine of this type is known from the state of the art, for example, DE 42 06 417. With this machine, there is the problem, on the one hand, of the pivoting of a bending beam bearing the bending tool being constructionally complicated and, on the other hand, of considerable space being required for the handling and the bending of the flat material in a front area in front of the clamping tools.
The object underlying the invention is therefore to improve a bending machine of the generic type in such a manner that with a space-saving construction of the bending machine the movements of the bending tool can be realized technically with simple means.
This object is accomplished in accordance with the invention, in a bending machine of the type described at the outset, in that the machine frame is designed to be laterally open at at least one of its transverse sides for the insertion of flat material in longitudinal direction of the bending edge and between the upper beam and the lower beam, that the bending tool is movable transversely to the clamping plane for passing through the bending positions and that in all the possible bending positions the bending tool carrier remains exclusively on the side of the clamping plane, on which a starting bending position of the bending tool is located.
The advantage of the inventive solution is to be seen in the fact that, on the one hand, it is possible to supply the flat material through the laterally open machine frame in a simple manner and the kinematics of the bending tool carrier are also simplified as a result such that this is not a hindrance even during complex bending operations.
The inventive solution is particularly advantageous in that elongated flat material, in particular, can be supplied in a simple manner and is also easy to handle and thus the bending machine can also be easily integrated into a production line, with which, for example, flat material coming from the coil or from a rolling unit can be processed.
As a result of the inventive design of the bending tool moving device which moves the bending tool transversely, i.e., at right angles or in any optional manner at an angle to the clamping plane, it is possible for the bending machine to be of a very compact construction and, in particular, for a front space in front of the clamping tools, into which the sheet metal to be bent projects, to be affected to as small a degree as possible by the bending tool moving device in order to obtain as great a degree of freedom as possible with respect to the possible bending operations and/or handling operations.
For such a laterally open design of the machine frame, it is fundamentally sufficient when an opening is present which extends in the direction of the clamping plane and is limited transversely to the bending edge and which is larger than an extension of the flat material to be supplied in this direction. It is, however, particularly favorable when the machine frame is designed to be open in the area of the clamping tools for the insertion of flat material between the clamping tools, as well, so that also flat material which has a greater extension transversely to the bending edge than, for example, the distance between a guide means of upper beam and lower beam relative to one another and the bending edge can already be inserted laterally between the clamping tools.
Such a design of the machine frame would also be conceivable when the machine frame has side columns; in this case, it would merely be necessary for the side columns to be provided with corresponding openings.
It is, however, particularly favorable when the machine frame is designed to be free from any side columns. A particularly advantageous design of the machine frame provides for this to extend essentially only between lateral end surfaces of the upper beam and the lower beam.
One advantageous type of design for the machine frame provides for the machine frame to have at least two frame units which are arranged to extend one after the other in a direction parallel to the longitudinal direction of the bending edge and which hold the lower beam and the upper beam so as to be movable relative to one another. Such a solution is of advantage, in particular, with a view to the efficient production of bending machines with lengths of the upper beams and the lower beams varying in size since the number of frame units can vary from bending machine to bending machine with the length of lower beam and upper beam.
In this respect, spaces are preferably arranged between the frame units. These spaces can, for example, also be used to provide handling devices for the flat material during bending which engage in the spaces and can thus be designed in a simple manner such that they can advantageously grip the flat material and position it for bending.
With respect to the design of the frame units themselves, it is favorable when each frame unit has a guide means for a defined movement of the lower beam and the upper beam relative to one another so that the guidance of upper beam and lower beam relative to one another is brought about each time at each of the frame units. The lower beam and the upper beam can also be designed in a constructionally advantageous manner, in particular, as a result of the plurality of frame units since the frame units each represent a stabilization of lower beam and upper beam relative to one another and so the stability of the lower beam and the upper beam in longitudinal direction of the bending edge has to be far less great than in machines, with which lower beam and upper beam extend self-supportingly between lateral frame units of the machine frame.
The guide means for lower beam and upper beam relative to one another can be of any optional design. For example, a linear guide means for moving the lower beam and the upper beam relative to one another would be conceivable.
It is, however, particularly simple from a constructional point of view when the lower beam and the upper beam are pivotable relative to one another about a pivot axis.
In this respect, the pivot axis is preferably located such that it is arranged at a distance from the clamping tools on a side thereof located opposite the bending tool.
A particularly advantageous constructional solution results when each frame unit has a lower beam carrier and an upper beam carrier which are movable by the guide means relative to one another and bear the lower beam and the upper beam, respectively, so that the guide means can be arranged at a sufficiently large distance from lower beam and upper beam.
In order to form a continuous machine frame from the individual frame units, these are to be connected to one another although they already have a connection to one another via a continuous lower beam and a continuous upper beam. Therefore, it is preferably provided for the lower beam carriers of the frame units to be rigidly connected to one another, wherein a continuous rigid connection between the upper beam carriers of the frame units is preferably provided in addition to the lower beam.
With respect to the drive for moving lower beam and upper beam relative to one another it is necessary for at least one of the frame units to have a drive for a relative movement of the lower beam and the upper beam with respect to one another. This one drive would, in principle, be sufficient.
It is, however, particularly favorable when the machine frame is constructed from individual modules and, in particular, each of the frame units has a drive for the relative movement of the lower beam and the upper beam.
With respect to the association of the bending tool carrier drive units with the machine frame, no further details have so far been given; one advantageous embodiment, for example, provides for a bending tool carrier drive unit for the respective bending tool to be associated with each of the frame units.
In order to obtain sufficient space for flat material to be inserted between the upper beam and the lower beam, it is preferably provided for the frame units to engage on the upper beam and the lower beam on a side facing away from the clamping tools.
A machine frame designed to be free from side columns may be produced particularly favorably with a machine frame consisting of at least two frame units of this type in that the frame units are arranged between lateral end surfaces of the upper beam and the lower beam and thus the machine frame is also automatically open in the area of at least one transverse side in order to insert flat material between the upper beam and the lower beam from this side.
With respect to the arrangement of the bending tool moving device, no further details have so far been given. In principle, it would be conceivable to design the inventive bending machine such that the bending tool moving device is arranged in the area of side columns of the machine frame.
However, in order to obtain a machine which is of as narrow a construction as possible and, in particular, a machine with an extension in longitudinal direction which is variable, it is preferably provided for the bending tool moving device to be arranged between lateral end surfaces of the beams. Such an arrangement of the bending tool moving device has, in addition, the advantage that this allows a more uniform supporting of the bending tool and so, as a result, xe2x80x94particularly in the case of long bending machinesxe2x80x94problems are also avoided with respect to the bowing of the bending tool under load.
It is even more advantageous, in particular, when the bending tool moving device extends, in all the bending positions, between the machine frame and a front limiting plane extending through the bending tool and at right angles to the clamping plane. Such a design of the bending tool moving device has the great advantage that no element whatsoever of the bending tool moving device and also of the machine frame is present in front of the front limiting plane and so the flat material can, in this area, project in an unhindered manner, be taken over by other machines or handled in any other manner. In addition, such a construction of an inventive bending machine also allows the possibility of arranging several machines to follow one another in the form of a production line, i.e., the possibility exists that the flat material which projects beyond the front limiting plane on a side located opposite the machine frame can be taken over by another machine in a simple manner.
With this solution it is, in particular, remarkable that the bending tool itself is the element which projects the most beyond the machine frame on a side of the clamping tools located opposite the machine frame and all the remaining machine parts of the bending machine, in particular, the machine frame itself and the bending tool moving device are located on the side of the front limiting plane facing the machine frame.
The inventive bending machine is even more advantageous when the bending tool moving device extends, in all the possible bending positions, between the machine frame and a front plane extending through the bending edge and at right angles to the clamping plane. As the front plane is located even closer to the machine frame than the front limiting plane, an even greater free space is created in this case on the side of the front plane located opposite the machine frame and this space may be utilized, on the one hand, for a plurality of bending operations and, on the other hand, for handling the bent flat material, as well.
With respect to the design of the bending tool carrier itself, no further details have been given in conjunction with the preceding embodiments. It is particularly advantageous when the bending tool carrier is also located, in all the possible bending positions, between the respective beam and a limiting plane intersecting the bending tool and extending at right angles to the clamping plane since, as a result, it is ensured that even the bending tool carrier does not project beyond this limiting plane and thus the bending tool itself is the only element of the bending machine which extends the furthest away from the clamping tools on a side thereof facing away from the machine frame.
It is even more advantageous when the bending tool carrier extends, in all the possible bending positions, between the machine frame and a front plane extending through the bending edge and at right angles to the clamping plane, and is thus arranged even closer to the machine frame, so that only the bending tool projects beyond the front plane on the side located opposite the machine frame.
In order to also be able to carry out bending procedures in opposite directions with the inventive bending machine, it is advantageously provided for the bending machine to have a bending tool allocated to the lower beam and a bending tool allocated to the upper beam.
In this respect, the bending tools are preferably designed in the same way and each driven with a bending tool moving device provided for each bending tool.
In order to avoid the bending tools hindering one another, it is provided, for example, for the bending tool not used for an operation on the flat material to be brought into the rest position.
This makes it possible for the bending tool used each time and the flat material which is possibly partially bent to be given bending spaces which are as large as possible.
It is particularly advantageous when the bending tool not used for an operation on the flat material is always in the rest position so that it can be assumed that the bending tool never represents any hindrance for any bending with the other bending tool when it is not being used.
This solution comprises all the instances of application, with which, during use of one of the bending tools, the other bending tool is always in the rest position. This solution does not, however, preclude the fact that, where appropriate for special operations, for example, for folding operations or other special bending operations or handling operations, both bending tools are used and engage on the flat material at the same time or immediately and quickly one after the other.
In order to allow as large a number of types and as large a range of bending operations as possible, in particular, with flat material which is already bent, it is preferably provided for a bending space free from machine elements to exist between the clamping plane and a respective bending tool with bending tool carrier when the bending tool is in the rest position, this space extending over an angular area of at least 90xc2x0 around the operative bending edge, i.e., the flat material can extend away from the clamping tools within this bending space unhindered by machine elements of the bending machine. Moreover, this bending space which is free from machine elements of the bending machine can also be utilized to carry out additional functions, for example, any handling by additional devices.
It is favorable, in particular, when the bending tool with the bending tool carrier, in the rest position, does not reach as far as the front plane but an additional bending space, which can then be utilized during the bending with the respectively other bending tool, remains between the tool and the front plane.
The bending space is preferably dimensioned such that it extends around the operative bending edge over an angular area of at least 110xc2x0. It is even more advantageous when the bending space extends around the bending edge over an angular area of at least 120xc2x0.
Such a bending space may be realized particularly favorably when the bending tool carrier is located close to a front surface of the respective beam in the rest position, i.e., is removed as far as possible from the front plane and is arranged in the direction of the respective beam.
One embodiment of an inventive bending machine having optimum bending possibilities provides for the bending tool moving device of the bending tool in rest position to be located outside the bending space defined by the angular area.
It is particularly favorable for simple bending kinematics when the bending tool has a bending nose with a curved pressure surface for acting upon one side of the flat material.
One advantageous embodiment therefore provides for the bending tool to be movable by the bending tool moving device between a starting bending position and an end bending position on a path about the respective bending edge which is predetermined in a defined manner such that the curved pressure surface and the side of the flat material acted upon move relative to one another in the form of an essentially slide-free rolling on one another.
The advantage of this embodiment is to be seen in the fact that as a result of the use of a curved pressure surface and the rolling of the curved pressure surface on the side of the flat material acted upon bending operations which are gentle for the flat material can be realized, on the one hand, with movements of the bending tool which can be carried out in a technically simple manner.
The advantage of this solution is to be seen, in particular, in the fact that no sliding of the bending tool relative to the flat material essentially takes place, wherein the movement of the bending tool required for this purpose can be brought about in a constructionally simple manner.
In principle, it would be conceivable to move the bending tool on the path provided for the inventive solution, for example, by means of numerical path controls. Such a solution does, however, have the disadvantage that large forces have to be generated and controlled exactly for the movement of the bending tool.
For this reason, it is preferably provided for the path of the bending tool to be predetermined in a defined manner by a mechanical path guide means so that no precise path control of the bending tool with the aid of large forces is necessary but merely a driving of the bending tool in such a manner that it follows the path guide means.
The path guide means may be realized in the most varied of ways. For example, it would be conceivable to provide a connecting link path for this purpose which is followed by a path follower. Such a connecting link path is, on the one hand, complicated to produce and, on the other hand, entails a considerable constructional size.
For this reason, one advantageous embodiment provides for the path of the bending tool to be predetermined by at least one pivoting movement. A pivoting movement has the great advantage that this may be realized in a simple manner suitable even for large forces and, in particular, is liable to fewer appearances of wear and tear than a guide means by means of a connecting link path, in a simple manner and without considerable mechanical resources.
The inventive path may be realized particularly favorably when the path of the bending tool is predetermined by way of superposition of at least two pivoting movements, wherein reference is made to the comments made above with respect to the advantage of the pivoting movements in comparison with connecting link guide means.
No further details have so far been given concerning the design and alignment of the bending nose.
One advantageous embodiment, for example, provides for the bending nose to face at least one of the clamping tools with a bending nose tip in all the bending positions, wherein with such an alignment of the bending nose only simple movements thereof are necessary in order to bend the flat material in an inventive manner.
The way, in which the curved pressure surface and the side of the flat material acted upon by the tool are intended to move relative to one another, has not been specified in detail in conjunction with the preceding explanations concerning the invention. It would, for example, be conceivable to configure the rolling along such that a contact line between the pressure surface and the side of the flat material acted upon migrates away from the bending edge.
The movement of the inventive bending nose may be realized particularly favorably when a contact line between the pressure surface and the side of the flat material acted upon moves in the direction of the bending edge on the side of the flat material acted upon during the pass through the bending positions from the starting bending position to the end bending position. This solution has the great advantage that, in relation to the clamping tools, no pivoting of the bending nose itself through large pivoting angles is required in order to fulfill the inventive condition of the essentially slide-free rolling on the side of the flat material acted upon.
With respect to the design of the pressure surface itself, no further details have so far been given. One advantageous embodiment, for example, provides for the pressure surface to have an apex line located closest to the respective clamping tool in the starting bending position and to extend away from the clamping tool proceeding from this apex line. Such a design of the pressure surface of the bending nose likewise offers a simple possibility for being able to carry out the bending of the flat material precisely with movements of the bending tool which are as simple as possible.
A particularly advantageous design of the pressure surface provides for this to have a front pressure surface section which is located so as to face away from the bending tool carrier and extends away from the apex line. Such a type of pressure surface is suitable, in particular, for carrying out bendings of the flat material through angles of up to 90xc2x0. It is even more advantageous when the pressure surface has a rear pressure surface section which faces the bending tool carrier and, located opposite the front pressure surface section, extends away from the apex line. Such a design of the pressure surface has the advantage that, in particular, large bending angles, in particular, bending angles of more than 90xc2x0 can also be realized with a simple movement of the bending tool.
Within the scope of the inventive solution, it is preferably provided for the contact line between the pressure surface and the side of the flat material acted upon to be located in the area of the front pressure surface section in the starting bending position and to move in the direction of the apex line during bending.
In this respect, it is particularly favorable when the bending nose is movable into such an end bending position, in which the contact line is located in the area of the rear pressure surface section so that as large a pressure surface as possible can be utilized during the bending procedure and a bending of the flat material through more than 90xc2x0 can be carried out, in particular, with simple movement kinematics.
With respect to the design of the bending tool moving device in detail, no further particulars have so far been given. In principle, the bending tool moving device can comprise all the conceivable forms of realization so far used with bending machines which fulfill the inventive requirements. A particularly advantageous development of the bending tool moving device provides for this to have a plurality of holding elements which engage in an area of the bending tool carrier facing the bending tool and are arranged at fixed distances from one another in a direction parallel to the longitudinal direction of the bending edge, these holding elements supporting the bending tool carrier in relation to the machine frame. Such a design of the support for the bending tool carrier relative to the machine frame has the advantage that, as a result, the stability of the bending tool carrier itself need notxe2x80x94as, for example, with bending machines with side columns and bending tool moving devices arranged in themxe2x80x94be configured such that this withstands the bending forces as a part extending freely between the side columns and, nevertheless, has a low degree of bowing under load. On the contrary, this solution of providing holding elements arranged at a distance from one another offers the possibility of supporting the bending tool carrier on the machine frame at a plurality of locations in its longitudinal direction and so the bending tool carrier need only be designed to be stable enough to have an adequate deformation stability over the distances between the individual holding elements.
The holding elements can, however, be used not only for the purpose of being able to reduce the stability of the bending tool carrier itself. On the contrary, the holding elements can also be advantageously used for serving as guide means for a defined movement of a point of engagement thereof on the bending tool carrier and thus also for contributing to the determination of the path, on which the bending tool moves while passing through the individual bending positions.
The holding elements are preferably designed such that they guide the point of engagement on a predetermined path which, superimposed with other movements, contributes to the path, on which the bending tool moves.
Such a guidance for the bending tool carrier may be designed mechanically in a particularly simple manner when the holding elements engage on the bending tool carrier in an articulated manner. In addition, it is of advantage when the holding elements are mounted so as to be articulated in relation to the machine frame.
It is particularly favorable when the holding elements represent connection bars which engage, on the one hand, on the machine frame in an articulated manner and, on the other hand, on the bending tool carrier in an articulated manner so that a path movement of the point of engagement of the connection bars on the bending tool carrier may be defined in a simple manner via these connection bars and, in addition, large forces can be transferred from the bending tool carrier to the machine frame in a simple manner via the connection bars in order to give the bending tool carrier the adequate form stability during bending.
Such a point of engagement may be selected particularly favorably when the holding elements engage on the beam, with which the respective bending tool is associated.
Apart from such an arrangement of a plurality of holding elements, further measures are required to move the bending tool carrier such that the bending tool, in the long run, describes the path required in accordance with the invention in a precise manner.
This may be realized particularly favorably, also with respect to the stability of the bending tool carrier itself, when the bending tool carrier moving device has a plurality of bending tool carrier drive units which are arranged so as to follow one another in a direction parallel to the longitudinal direction of the bending edge for moving the bending tool between the starting bending position and the end bending position.
Since, with the inventive bending machine, the bending tool can also be expediently positioned in a rest position, it would, for example, be conceivable to reach the rest position by moving the entire bending tool moving device between a starting bending position and the rest position. It is, however, particularly favorable when the bending tool can also be moved by the bending tool carrier drive units between the rest position and the starting bending position.
In order to move the bending tool carrier, it is preferably provided for the bending tool carrier drive units to engage on the bending tool carrier at a point of engagement and move this between the starting bending position and the end bending position on a path predetermined in a defined manner. As a result of superposition of this path predetermined in a defined manner with additional path movements, for example, the path movements predetermined by the holding elements, the movement of the bending tool required in accordance with the invention may be expediently achieved on the path predetermined in a defined manner.
In principle, it would be conceivable, for example, to design the bending tool carrier drive device such that it guides the point of engagement on the path in the form of a numerically controlled path movement. However, this is complicated, on the one hand, with respect to the control resources and, on the other hand, also with respect to the forces to be generated for the path movement.
For this reason, it is preferably provided for the path to be predetermined by a pivoting movement about a pivot axis fixed in relation to the machine frame.
In the simplest case, the bending tool carrier drive units are designed in this respect such that they can be driven by a drive to carry out the path movements.
In this respect, a single drive will also be sufficient for a plurality of bending tool carrier drive units. It is, however, particularly advantageous when each of the bending tool carrier drive units can be driven by its own drive.
With respect to the design of the bending tool carrier drive units themselves, no further details have been given. One particularly advantageous embodiment provides, for example, for each of the bending tool carrier drive units to comprise a drive arm which can be pivotally driven, is pivotable at a first end about an axis fixed in relation to the machine frame and is pivotally connected to the bending tool carrier at a second end via an elbow joint. Such a design of the bending tool carrier drive units has the advantage that a definable movement of the bending tool carrier for determining the path of the bending tool can be realized as a result in a simple manner.
A particularly advantageous kinematic arrangement provides for each of the bending tool carrier drive units to have an elbow lever drive system for moving the bending tool carrier since complex movements can be generated with such an elbow lever drive system in a simple manner by adjusting the length of the elbow levers.
In order to be able to favorably define the path of the bending tool relative to the machine frame, it is preferably provided for a first lever of the elbow lever drive system to be pivotable about an axis fixed in relation to the machine frame.
In this respect, the elbow lever drive system could, in principle, be optionally actuated in that the drive engages on one of the levers of the elbow lever drive system. It is particularly favorable when the pivotally drivable drive arm forms the first lever of the elbow lever drive system.
With respect to the design of the second lever, it would be conceivable to provide for this purpose a special second lever which, for its part, again acts on the bending tool carrier. A solution, with which the bending tool carrier forms at least part of a second lever of the elbow lever drive system, is, however, mechanically favorable.
In order not to be tied exclusively to pivoting movements with respect to the determination of the movement of the bending tool carrier, a particularly favorable solution of the inventive bending tool carrier drive unit provides for the drive arm to be designed so as to be variable in length with respect to its distance between the first end and the second end. As a result, an additional translatory movement can be generated in addition to the pivoting movements.
This translatory movement may be used to provide the path provided for the bending tool from the starting bending position to the end bending position, in addition, with path corrections.
A solution is, however, particularly favorable, with which the length variability of the drive arm is used to move the bending tool back and forth between the starting bending position and the rest position.
For this purpose, it is expedient for the drive arm to be adjustable via a drive so as to be variable in length. Such a drive can, in principle, be a separate drive, with which the length of the drive arm can be adjusted at any time. This would be of advantage, in particular, when path corrections are also intended to be carried out by way of the length adjustment during the movement of the path of the bending tool between the starting bending position and the end bending position.
It is, however, particularly simple from a constructional point of view when the drive for pivoting the drive arm also serves as a drive for the length adjustment of the drive arm so that the length adjustmentxe2x80x94for example, for moving the bending tool between the rest position and the starting bending positionxe2x80x94and the movement of the bending tool on the desired path can be realized by means of one drive.
The length adjustment of the drive arm could, in principle, be brought about, for example, by a spindle adjusting means or any other adjusting mechanism. A particularly favorable solution does, however, provide for the drive arm to be variable in length on account of an elbow lever mechanism.
One form of realizing such an elbow lever mechanism provides for the drive arm to comprise an arm section extending from the first end as far as a center joint and an arm section extending from the center joint as far as the second end.
With such an elbow lever mechanism, the length adjustment of the drive arm can be realized in a particularly simple manner when the elbow lever mechanism can be secured in different extended positions to determine different lengths of the drive arm.
Such a determination of different extended positions may, in the simplest case, be brought about by blocking the movement of the arm sections relative to one another or also by locking the center joint in different positions.
In order to be able to determine these extended positions in a controlled manner, it is preferably provided for the elbow lever mechanism, for their determination, to be blocked by a blocking device which preferably acts either on the arm sections themselves or on the center joint.
With respect to generating the pivoting movements of the drive arm, no further details have so far been given. It would, for example, be conceivable to arrange the drive arm on a shaft and to initiate the pivoting movement thereof via this shaft. A particularly favorable solution does, however, provide for a pivot drive to engage on the first arm section of the elbow lever mechanism for pivoting the drive arm.
The pivot drive is preferably designed such that it engages on the center joint.
A solution which is particularly favorable from a mechanical point of view and with which the bending tool carrier co-acts as second lever of the elbow lever drive system provides for the bending tool carrier to be provided with arm extensions which extend in the direction of the drive arm and each of which forms with the bending tool carrier the second lever of the elbow lever drive system. In this respect, it is particularly favorable when the arm extensions are rigidly connected to the bending tool carrier and thus form one unit with it each time.
With respect to the arrangement of the bending tool moving device, no further details have so far been given. One advantageous embodiment, for example, provides for the bending tool moving device to engage at least partially on the beam, with which the bending tool is associated. Such an engagement on the beam, with which the bending tool is associated, has the advantage that, as a result, it is possible to support the guide means of the bending tool in part at least as close as possible to the clamping tools. If this takes place via a holding element as already described, it is preferably provided for each of the holding elements to engage on the respective beam.
An additional, advantageous support for the bending tool moving device is preferably brought about in that the bending tool carrier drive unit is arranged on the beam carrier of the respective beam and thus is likewise positioned on the machine frame in a suitable and space-saving manner.
Since, as a result of the use of an elbow lever mechanism, the movement of the elbow joint relative to the first arm section and also relative to the machine frame cannot be determined, it is preferably provided for the elbow joint to be movable along a defined path during the length alteration of the drive arm. As a result, the possibility is created of guiding the elbow joint in a definitive manner and thus of also predetermining the movement of the bending tool exactly.
In the simplest case, it is provided for the path to extend in a straight line.
The realization of the guidance of the elbow joint along a path may be achieved in a particularly simple manner in that a path follower which extends along a connecting link predetermining the path is arranged on the elbow joint, wherein the connecting link is preferably arranged on the machine frame.
In order to be able to advantageously determine different positions of the bending tool by means of the path, it is provided for the connecting link to be adjustable into different positions relative to the machine frame.
The guidance of the elbow joint along the path may be used particularly advantageously for determining the movement between the rest position and the starting bending position of the bending tool. For this reason, it is preferably provided for the path follower to be movable along the connecting link during the movement of the bending tool from the rest position into the starting bending position.
After reaching the starting bending position, a further guidance of the elbow joint by means of the connecting link is no longer necessary in one particularly advantageous case since the starting bending position is preferably reached when the elbow lever mechanism is in its extended position determinable by the blocking device. For this reason, it is preferably provided for the path follower to lift away from the connecting link in the bending positions following the starting bending position.
In order to be able to process, in particular, elongated flat material with an inventive bending machine, it is preferably provided for the machine frame to be designed to be laterally open at at least one of its transverse sides for the insertion of flat material in longitudinal direction of the bending edge and between the upper beam and the lower beam. Such a design of the machine frame is advantageous, in particular, for flat material withdrawn from a coil or for long flat material parts which are to be fed laterally in a production line.